Does a boost leak register on the boost gauge?

[daveyfx]

I'm going to be running a boost leak test on my '99 GST tomorrow when the weather "nicens" up.

Out of curiosity - will boost leaks always be evident by the readout on the boost gauge? I have an aftermarket (Defi) boost gauge and it will read out 15 psi and hold it steady. The only problem is that my car is absolutely pathetic in the acceleration department and the first and easiest thing to look for is boost leaks.

Thanks in advance

 

[pooya]

I have horrible leaks everywhere...but my gauge still says that im boosting strong. 15+

 

[DGajre777]

If the boost gauge is a boost/vacuum gauge, then yes the vacuum part in Hg will go lower that what it normally does.

 

[~laser_craver~]

On your average boost gauge, it will not make a difference. You can usually tell by the performance of the car.

 

[CanadianTSi]

It will not show on the gauge.

The gauge will show a constant 15(or whatever you are running) but the turbo is actually having to produce 20+psi because some of it is leaking out before it gets to the Intake Manifold.

 

[pooya]

It will not show on the gauge.

The gauge will show a constant 15(or whatever you are running) but the turbo is actually having to produce 20+psi because some of it is leaking out before it gets to the Intake Manifold.

hmm...
Does the ecu know how much psi it is actually pushing?
Because ever since I started getting these horrible leaks, my turbo makes this really loud whistle (not the turbo spooling itself, but another higher pitch whistle) and I was wondering if I am over working my turbo.
I'm on a stock t25, and when I first got the car a couple months ago, I had no shaft play, and I checked it a couple days ago, I have some minor shaft play.

Sorry for hijacking your thread...
any idea?

 

[CanadianTSi]

If you have boost leaks then yes your pushing the turbo way to hard shortening it's lifespan...

 

[Bo0O0ostedDSM]

I can't tell if I have a boost leak from my (boost) gauge, but I usually can feel it.

 

[daveyfx]

Thanks for the responses so far guys. I just performed the leak test using a 7 gallon tank of compressed air and could not get my aftermarket gauge to read ANY boost (yes, it's a mechanical gauge).

I felt what I think is a pretty serious leak coming from the section where my 14b's j-pipe bolts down the the outlet of the compressor.

This just goes to show what can happen if you decide you don't need that gasket for the j-pipie. I thought simply slathering some blue RTV all over would suffice but obviously not.

@ me.

 

[importboost]

Whenever I have a boost leak, my vac. reads less than it should be. Normal vac. should be 18inHg.

 

[daveyfx]

Whenever I have a boost leak, my vac. reads less than it should be. Normal vac. should be 18inHg.

My vac. has been sitting between -18 and -20 Hg but I definitely have a pretty severe leak. I didn't have the aftermarket boost gauge installed until after this leak so I couldn't tell you what my vac. would normally sit at.

 

[The_EE]

I have only one boost leak, its on the throttle body otherwise I have none and I normally show about 12 vac.